Lack of summer monsoons forces Arizona grower to fire up pumps

Like other pecan growers in southeastern Arizona, Danny Tingle, who manages Sunland farms near Cochise, counts on summer monsoon rains to provide extra insurance for his sprinkler-irrigated trees.

From about July 1 to mid- to late August, it is monsoon season in the desert; the booming thunderstorms can provide as much as half of the area’s annual precipitation.

“Even when we have adequate groundwater for our trees, as we do this year, it’s still nice to get a couple weeks where, if we have problems with our pumps, we can turn them off for a few days of maintenance,” Tingle says. “If we get behind on our irrigation, the monsoons make it easier to catch up.”

This year, though, the monsoons didn’t come.

“We’ve been irrigating non-stop,” he says. “I’ve been walking on eggshells to make sure I didn’t get behind, knowing that if I make a mistake and don’t apply enough water, or if I have to shut down the sprinklers for any reason, I’m not going to get any water to make up the difference. Success often depends on how well you manage irrigation late in the season.”

While the summer rains are unpredictable, they’ve been more variable since 2003, Tingle notes. “This year, 25 miles north of us they’ve received more than normal rainfall.”

Sunland Farms continues to expand pecan production, and Tingle now has 135 acres of bearing Western Schleys and 75 acres of non-bearing trees.

M of the terminal buds produced clusters this year, each with about four nuts. “There are a lot of clusters out there — about average for an on-year like this one,” he says.

One of his goals is to reduce the annual fluctuation in production of the alternate-bearing trees.

“We’ve learned how much we can even out production from year to year by controlling aphids,” Tingle says. “They suck a lot of energy out of the trees, preventing them from coming back with a strong crop the next year.”

Aphids — yellow and black-margined in early summer and black in late summer — have been average in number this year. Tingle credits that to his control program, which includes systemic insecticides, applied in late March, mid- to late April and, if necessary, a contact insecticide in late August.

Monsoons can be helpful in controlling aphids, he says. “Generally, we get the first flush of aphids in June and then the heavy rains in July wash them off the leaves.”

Because the trees can’t get enough zinc from the soil, Tingle uses an air-blast sprayer to apply zinc sulfate, plus a little urea, to improve zinc absorption by the trees. He sprays the material five or six times in the spring on his 2- to 6-year-old trees. Older trees get zinc at least once in the spring. Trees that are hedged received three or more zinc treatments in the spring, depending on the amount of new growth.

Tingle provides nitrogen in the form of UAN 32 with irrigation, based on leaf analysis throughout the season.

“We often use more than is recommended by the university,” he says. “If the crop is there, you have to give it what it needs. We’ve found that this higher rate of nitrogen helps reduce the differences in production from one year to the next.